problems after 3400 top swap

[fat rabbit]

About a year ago I started gathering info & parts to perform a 3400 top swap, about a few months ago I started to notice coolant missing from the reservoir and decided it was time to throw everything on.
1. 99-05 cylinder heads(resurfaced, 3 angle valve job, cleaned and checked)
2. 01 lower and upper intake(cleaned and checked for cracks)
3. 56mm throttle body
4. Used newer style alternator and bracket
5. Used newer style EGR and connecting pipe
6. Used multec 2 injectors, 55psi fpr and correct fuel injector harness(rewired to my harness)
7. New AC delco thermostat and Delphi temp sensor
8. New bolts and gaskets
9. Tuned ecm for larger injectors w/lower fan settings

Last month I started removing everything down to block, inspecting the cam with the lower intake off I noticed pitting on the exhaust lobe to cylinder 4. Looked back at my lifters and also found pitting on the roller to the same lobe, so I talked it out with my buddy helping me and we pulled out the engine to what turned into replacing more parts.
1. Sealed Power stock grind cam
2. AC Delco lifters
3. AC Delco timing chain and gears
4. 1' 3/8" thick radiator(found it at the junkyard and felt like I couldn't pass it up)
5. New AC Delco radiator cap
6. New AC Delco spark plugs and wires(gapped .60)

Putting everything back together I was retarded and torqued down the valve train before setting the timing and bent the intake valve on cylinder 1, so I had to remove the rear head and brought it back down to the machine shop for a replacement valve. I put everything back together and the car fired up without any check engine lights.

Fast forward from 2 weeks of running to my present problem(s) When ever I start it up in the morning and put it in drive from a stop under load the engine hesitates at around 1500-2000rpm and as it warms up it becomes less noticeable but still present, its vary consistent. The other problem I've been having is the car heating up to operating temp in sometimes less then a min of driving then the temp will lock in at 208 degrees, weather driving on the highway, city, 93 degree days, 63 degree days, 3 hour trips or even 10 min trips it won't hardly if ever drop a degree or go up in temp.

A few things I didn't like about the swap was when unbolting the down pipe the nuts stripped so I cut the pipe right before the cat to remove it/fix it and had a 2' 1/5" coupler welded in and I thought I could re pin my harness to the different pigtail the injector harness came with but found out the hard way it wouldn't work so I had the newer pigtail soldered to my harness.

I did do a compression test on the block with the new heads cylinder heads trying to figure out my misfire codes prior to figuring out I had a bent valve 1=0psi cylinder 2=145psi cylinder 3=130psi cylinder 4=140psi cylinder 5=130psi and cylinder 6=130psi I didn't do a compression test after re installing the rear cylinder head. I also tested the fuel pressure and it goes up too 55psi but within a min drops to around 42psi, I'm thinking it maybe the juckyard injectors that are causing a hesitation and leaning out the engine allowing to heat up higher then normal?

I apologize about the long post, I've been racking my brain at this for awhile lol Any help into the right direction would be greatly appreciated.

[fat rabbit]

During lunch break I decided to play around with my car some, I started by unplugging my radiator fans and starting the engine. Using a scan gauge I watched the temps steadily climb up past 208 degrees all the way up to almost 220(I turned off the engine then) During the warm up I kept my hand on the upper radiator hose to get an idea of when the thermostat is opening and it felt like it was opening up at around 207-208 degrees, right were the temp gauge pegs at. When I did turn off the engine I jammed a thermometer in where the bleeder screw goes and noted a -10 degree difference from what the temp sensor was reading, could I just have a bad thermostat not opening till 207-208 degrees?

When playing with the temps I noticed and I must have been blind before because the wire harness that connects the crank sensor in the back of the block to the DIS was melted and fusing to the EGR and pipe, that maybe why randomly the engine wouldn't start right away. So I rerouted the harness for the time being till I have time to pick up another one. On the way home I unplugged the external crank sensor but noticed no difference in the way the car acts, would that harness melting give off the hesitation the engines been having?

I swear the sooner I get this problem solved and off my mind, the better I'll be lol

[fat rabbit]

Yesterday when leaving to work I noticed a large cloud of white smoke coming out of my tail pipe, I couldn't tell if I was burning coolant or not. When the engine warmed up on the way to work it went away. This repeated on the way home so I hooked up a coolant pressure tester, pumped it up to 15psi and about 15min later it dropped down to around 11psi. Is this normal? It didn't blow out any white smoke today, maybe I'll blame it on moisture.

Not liking the readings I got form the coolant test, I hooked up a compression tester to the engine.
Cylinder #1 (160psi)
Cylinder #2 (150psi)
Cylinder #3 (165psi)
Cylinder #4 (159psi)
Cylinder #5 (160psi)
Cylinder #6 (165psi)
I'm ordering another GM gasket and bolts for the front, I don't know if that's the cause of the hesitation and engine running hotter then the norm. To be honest I really don't want to dig back into this engine for a 3rd time within a month, could a 15psi cause a noticeable difference in how the engine runs?

[fat rabbit]

I got around to playing with the car again this weekend, I've learned that if I unplug the egr valve the hesitation goes away. The engine feels down on power when I do that but it so much more smoothly compared to it plugged in. With that in mind I thought my egr maybe sticking so I unbolted it and soaked it in/cleaned it out with carb cleaner but it made no difference, even a new egr made no difference.

I did a KOEF test with the MAP sensor and it reads what the local weather station reports, I find it strange that the MAP sensor reads 11.2-11.5 "hg at idle yet hooking up vacuum gauge reads 18 "hg at idle? I'm getting a 5v ref from the ECM KOEF, plugging in a new map sensor doesn't change any of the readings.

I'm starting to feel the source of my problems is the engine running too lean giving me a hesitation and a bit too hot running engine. If i unplug the upstream O2 sensor the hesitation becomes less noticeable, unplugging the down stream O2 sensor with it makes the engine behave just like unplugging the EGR valve.

My old setup never ran like this before, the only things that changed engine management wise was ECM, injectors, and regulator. Is there a way to tell if the tuned ECM is the problem or is the only way by me plugging back in the old ECM/injectors/regulator?

[Purple pit]

I am shocked that you are just talking to yourself. Sorry that I can't help.

[3400-95-Modified]

You would have to get some data logs to verify if the ECM is happy with that setup... Unplugging the downstream O2 should never change anything (I don't even have one on my car) and same with the EGR since that doesn't even open unless your cruising on the highway.

The compression test wont really show a seeping head gasket... Only way to see that is get it hot, let it sit then start it up... With the pressure in the system it should dump some coolant in the cylinder thats leaking and steam again. Another thing is to check the plugs and see if any look way clean, or have an oddball color to them. Leaking coolant will steam clean a cylinder easily.

[fat rabbit]

I've been communicating with Ben about my problem and the tune is no longer in question, its not when I unplug the downstream O2 were it changes but when I unplug both of them. What I found strange was that when I unplugged the upstream O2 the computer never turned on the check engine light, it wasn't until I unplugged both were it turned on the light. I wish I had the tools to data log but at the moment I don't, maybe the in the future.

When I did the last compression test I noticed the spark plugs from cylinder #2 and #4 were more clean then the rest yet its hard for me to tell as the plugs were still fairly new, one problem I did notice though with the spark plugs was that 2 of them had bent porcelain towers so I did another tune up a few days ago. I do keep finding traces of oil around the front head gasket by the edge of cylinder #2, not alot but just enough to leave a vary light film of oil, I have new head gasket and bolts laying around but don't want to tare apart the head yet till I know that its the cause of my engine problems. For some reason the engine only burned coolant one random day during cold starts, other then that day its never shown any signs of losing coolant.

Yesterday I put in another thermostat in and let the engine cool off, I started it up 5 hours later and sprayed down the engine for vacuum leaks..... I think I'm going blind, all the bolt mounting tabs to the upper intake are cracked. So I'll be off to the junkyard this weekend to pickup another upper intake, that could just be the source of my vacuum leak. I'm also going to pick up so new O2 sensors as upstream was last replaced in 04 and downstream has never been touched in its life.

Thanks for the replies, I was starting to feel alone there for a bit lol

[Purple pit]

More back ground please. What plugs are you using, what is the head gasket size and what else did you do to this engine? These bent plugs are making me worry.

[fat rabbit]

The plugs that had 2 of 6 bent were AC Delco 41-940's now I'm running AC Delco 41-101's, as for head gaskets I have OEM GM graphite head gaskets for a 3100 installed. I don't know for sure but I don't think they were bent being in the engine, I think they were bent from the beginning(poor QC) and I threw them in not really inspecting them before hand.

[3400-95-Modified]

Just a fyi, oil will typically never leak from a head-gasket, any oil you seen accumulating there will be coming from the lower intake valley, PS pump, or the valve covers... it just drips down and follows the gasket and drips off that. There isn't any oil that run through the head-gasket, all the drain back holes go to the valley.

[fat rabbit]

I'd like to thank you Purple Pit and 3400-95-Modified.

The problem to the hesitation ended up being the cracked upper intake, taking off the old one I could see the cracks going into the runners. I picked up another one from the junkyard and for the past 2 days I haven't had any hesitation issues at all, the MAP sensor is reading 13"hg at idle now compared to 11.2"hg at idle. I don't know if 13"hg is still low or not, I hooked up a vacuum gauge after I installed the good upper intake and I get around 17" to 18" at idle.

As for the engine holding a consistent 207 degrees, I think I've narrowed it down to a part/half clogged radiator. Next week when I get paid I'm going to pick up a new radiator, does anyone have the part number to a 1' 3/8" thick radiator?

[3400-95-Modified]

There are a bunch of listings on Rockauto... The max cooling ones seem to be the 1" think vs the 5/8" There is one 1 3/8 thick listed but it's also the cheapest one.

Nissens #69220 1 3/8 core $58.99

Vista Pro #432427 w/max cooling 1" core $80.79

Or VARIOUS MFR Part # GM3010193 1" core w/heavy duty cooling $91.79

they just get more expensive after that...

[Purple pit]

Damn, should have thought of that. I just thought I was the only person that could find a way to crack an upper. Ben sent me a photo of it when it was at his shop.

I help when I can and if I can't then I try to support.

[19Cutlass94]

When I got a radiator for my car, I went with the thicker ( I think 1" ) one, and it was actually a two core radiator. Even if the larger one is a little more money, bet to opt for that option.

[fat rabbit]

I wasn't aware they made 2 core radiators for w-body's, I'm positive that even my 1' 3/8" is a 1 core but I could be wrong. Vista Pro #432427(1') claims to be a 1 row as does Vista Pro #432387(1' 3/8") yet the 1' cost a Mcdouble more per RockAuto?

I'm glad I'm not alone with cracking upper intakes, I was a little embarrassed when I found the problem. This time I torqued all the bolts 5 ft-lbs at a time gradually working my way up to 18 ft-lbs.